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Performance of electrocatalytic reactions depends on not only the composition and structure of the active sites, but also their local environment, including the surrounding electrolyte. In this work, we demonstrate that BF2(OH)2− anion is the key fluoroborate species formed in the mixed KBi/KF (KBi=potassium borate) electrolyte to enhance the rate of the oxygen evolution reaction (OER) at near‐neutral pH. Through a combination of electrokinetic and in situ spectroscopic studies, we show that the mixed KBi/KF electrolyte promotes the OER via two pathways: 1) stabilizing the interfacial pH during the proton‐producing reaction with its high buffering capacity; and 2) activating the interfacial water via strong hydrogen bonds with F‐containing species. With the KBi/KF electrolyte, electrodeposited Co(OH)2 is able to achieve 100 mA/cm2 at 1.74 V, which is among the highest reported activities with earth‐abundant electrocatalysts at near neutral conditions. These findings highlight the potential of leveraging electrolyte‐engineering for improving the electrochemical performance of the OER. [ABSTRACT FROM AUTHOR]

Anionocages have been developed as a unique family of hydrogen bonded cages. However, strategies for constructing anionocages are mainly limited to that based on (PO43−)‐bisurea coordination, neither the ligands nor the anions lack the simplicity and diversity of the maturely developed analogues based on metal coordination (i.e. metallocage). We report herein a more simple strategy for anionocages design based on (RPO32−)‐monourea coordination, utilizing monourea rather than bisurea as the hydrogen binding donor, and RPO32− rather than PO43− as the acceptor. Two fluorescent, quadruple helicate anionocages were constructed by a bis‐monourea ligand, and dianions PhOPO32− (H1) or HOPO32− (H1A), respectively, which were capable of encapsulating a series of cation guests. As revealed by molecular modeling, H1 features remarkable guest‐adaptive cavity breathing without change of the quadruple helicate topology, which allowed the encapsulation of different sized guests in an "induced fit" manner. [ABSTRACT FROM AUTHOR]